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<b>let </b><font color="Maroon" title="c3">a</font>, <font color="Maroon" title="c4">b</font> be   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">L</font>;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:9_1_1"/><i><font color="Green" title="E10">A2</font></i>: 
<font color="Maroon" title="c3">a</font> <a href="sheffer1.html#R1" title="SHEFFER1:pred.1">is_a_complement'_of</a> <font color="Maroon" title="c2">x</font>
 <b>and </b><br/><a NAME="E2:9_1_1"/><i><font color="Green" title="E11">A3</font></i>: 
<font color="Maroon" title="c4">b</font> <a href="sheffer1.html#R1" title="SHEFFER1:pred.1">is_a_complement'_of</a> <font color="Maroon" title="c2">x</font>
 ;<br/>

<font color="Maroon" title="c4">b</font> = 
<font color="Maroon" title="c4">b</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <span class="p1">(<span class="default"><a href="sheffer1.html#K1" title="SHEFFER1:func.1">Top'</a> <font color="Maroon" title="c1">L</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="sheffer1.html#D2" target="_self" title="SHEFFER1:def.2">Def2</a></i>
<br/>.= 
<font color="Maroon" title="c4">b</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">x</font> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <font color="Maroon" title="c3">a</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9_1_1"><i><font color="Green" title="E10">A2</font></i></a>, <a class="ref" href="sheffer1.html#D6" target="_self" title="SHEFFER1:def.6">Def6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c4">b</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c2">x</font></span>)</span> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c4">b</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c3">a</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="lattices.html#D11" title="LATTICES:def.11">LATTICES:def 11</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c2">x</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c4">b</font></span>)</span> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c4">b</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c3">a</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="lattices.html#D6" title="LATTICES:def.6">LATTICES:def 6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c2">x</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c4">b</font></span>)</span> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c4">b</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="lattices.html#D6" title="LATTICES:def.6">LATTICES:def 6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="sheffer1.html#K2" title="SHEFFER1:func.2">Bot'</a> <font color="Maroon" title="c1">L</font></span>)</span> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c4">b</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E2:9_1_1"><i><font color="Green" title="E11">A3</font></i></a>, <a class="ref" href="sheffer1.html#D6" target="_self" title="SHEFFER1:def.6">Def6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c2">x</font></span>)</span> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <font color="Maroon" title="c4">b</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9_1_1"><i><font color="Green" title="E10">A2</font></i></a>, <a class="ref" href="sheffer1.html#D6" target="_self" title="SHEFFER1:def.6">Def6</a></i>
<br/>.= 
<font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <span class="p1">(<span class="default"><font color="Maroon" title="c2">x</font> <a href="lattices.html#K1" title="LATTICES:func.1">"\/"</a> <font color="Maroon" title="c4">b</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="lattices.html#D11" title="LATTICES:def.11">LATTICES:def 11</a></i>
<br/>.= 
<font color="Maroon" title="c3">a</font> <a href="lattices.html#K2" title="LATTICES:func.2">"/\"</a> <span class="p1">(<span class="default"><a href="sheffer1.html#K1" title="SHEFFER1:func.1">Top'</a> <font color="Maroon" title="c1">L</font></span>)</span>
<b>by </b><i><a class="txt" href="sheffer1.html#E2:9_1_1"><i><font color="Green" title="E11">A3</font></i></a>, <a class="ref" href="sheffer1.html#D6" target="_self" title="SHEFFER1:def.6">Def6</a></i>
<br/>.= 
<font color="Maroon" title="c3">a</font>
<b>by </b><i><a class="txt" href="sheffer1.html#E1:9"><i><font color="Green" title="E9">A1</font></i></a>, <a class="ref" href="sheffer1.html#D2" target="_self" title="SHEFFER1:def.2">Def2</a></i>
;<br/>
<b>hence </b><a NAME="E4:9_1_1"/>
<font color="Maroon" title="c3">a</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c4">b</font>
 ;<br/>


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